Cleaning cart with rechargeable power supply

ABSTRACT

A cart that moves through a three-dimensional object printing system includes a platform and a cleaning device configured to remove material from a surface as the platform passes the surface. The cart further includes a rechargeable power supply configured to be connected to the cleaning device. A controller onboard the cart is operatively connected to the rechargeable power supply and the cleaning device. The controller is configured to connect the rechargeable power supply to the cleaning device and operate the cleaning device to clean the surface.

PRIORITY CLAIM

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 14/693,066, which is entitled “Cleaning Cart WithRechargeable Power Supply,” which was filed on Apr. 22, 2015, and whichissued as U.S. Pat. No. 9,987,805 on Jun. 5, 2018.

TECHNICAL FIELD

This disclosure relates generally to printing systems, and inparticular, to maintenance devices used in three-dimensional objectprinting systems.

BACKGROUND

Digital three-dimensional object manufacturing, also known as digitaladditive object manufacturing, is a process of making athree-dimensional solid object of virtually any shape from a digitalmodel. Three-dimensional object printing is an additive process in whichone or more ejector heads eject successive layers of material on asubstrate in different shapes. Typically, ejector heads, which aresimilar to printheads in document printers, include an array of ejectorsthat are coupled to a different source of material. Ejectors within asingle ejector head can be coupled to different sources of material oreach ejector head can be coupled to different sources of material toenable all of the ejectors in an ejector head to eject drops of the samematerial. Materials that become part of the object being produced arecalled build materials, while materials that are used to providestructural support for object formation, but are later removed from theobject are known as support materials. Three-dimensional object printingis distinguishable from traditional object-forming techniques, whichmostly rely on the removal of material from a work piece by asubtractive process, such as cutting or drilling.

A previously known three-dimensional object printing system 10 is shownin FIG. 12. In the view depicted in that figure, a platform 14, called acart, includes surfaces 18 (FIG. 11) that slide upon track rails 22 toenable the cart to move in a process direction P between printingstations, such as the printing station 26 shown in FIG. 12.Alternatively, carts can include wheels configured to roll along tracks,or other types of acceptable mobility mechanisms. Printing station 26includes four ejector heads 30 as shown in the figure, although fewer ormore ejector heads can be used in a printing station. Once the cart 14reaches the printing station 26, the cart 14 transitions to and movesalong precision rails 38 through the printing station. Precision rails38 are cylindrical rail sections that are manufactured within tighttolerances to help ensure accurate placement and maneuvering of the cart14 beneath the ejector heads 30. Linear electrical motors are providedwithin housing 42 to interact with a magnet inside housing 46, which isconnected to the lower surface of the cart 14. The motors generateelectromagnetic fields that interact with the magnet to propel the cartalong the track rails 22 between print stations and along the precisionrails 38 within the printing stations. Once the cart 14 is beneath theprinting station 26, ejection of material occurs in synchronization withthe motion of the cart. Electrical motors (not shown) are operativelyconnected to a gantry to which the ejector heads are mounted to move theejector heads in an X-Y plane that is parallel to an upper surface ofthe cart 14 as layers of material are formed in the object. Additionalmotors (not shown) move the printing station 26 vertically with respectto the cart 14 as layers of material accumulate to form an object.Alternatively, a mechanism can be provided to move an upper surface ofthe cart 14 vertically and horizontally for formation of the object.Once the printing to be performed by a printing station is finished, thecart 14 is moved to another printing station for further part formation,layer curing, or other processing.

An end view of the system 10 is shown in FIG. 11. That view depicts inmore detail the surfaces 18 that rest upon the rails 22 that extend fromand above the electrical motor housing 42. As the motors generateelectromagnetic fields that interact with the magnet in housing 46, thesurfaces 18 of the cart 14 slide along the track rails 22. At theprinting station, the bearings 34 of the cart 14 contact the precisionrails 38 in an arrangement that facilitates accurate positioning of thebuild platen on the cart 14. Specifically, bearings 34 are positioned ata right angle to one another on one of the rails 38 to remove fourdegrees of freedom of the cart 14, while the other bearing 34 rests onthe other rail 38 to remove one more degree of freedom. Gravity andmagnetic attraction between the electrical motor and the magnet in thehousing 46 hold the bearings 34 in contact with the rails 38.

When carts are not present underneath the ejector heads 30, errant dripsof materials can fall from the ejector heads and produce undesireddebris and contamination on the precision rails 38 and the housing 42.In order to produce three-dimensional objects with acceptable quality,the motion of the cart 14 beneath the ejector heads 30 needs to beprecise. If materials from the ejector heads collect where the bearings34 interface with the precision rails 38, the linear velocity of thecart is disrupted and the quality of the printed object is affected.Additionally, the collection of material drops on top of the housing 42may also disrupt the linear velocity of the cart and affect the qualityof the printed objects. Therefore, improvements in three-dimensionalobject printing systems that help eliminate the contamination on theprecision rails and motor housing that affects the accuracy of theplacement and movement of the cart would be beneficial.

Regular maintenance to the ejector heads 30 and other printing stationsis beneficial for maintaining accurate and efficient operation of theprinting system 10, and for preventing material and other contaminantsfrom accumulating on the precision rails and motor housing. Conventionalthree-dimensional object printing system maintenance devices oftenrequire lengthy interruptions of the printing process, and includecomplex machinery beyond the components necessary for three-dimensionalobject printing that can increase the machine footprint of the system.One example of a conventional maintenance device includes a maintenancecabinet separate from the printing system 10 that can be positioned nextto a printing station to be maintained. The cabinet contains toolsusable to maintain the printing station. In another example, an ejectorhead is moved to engage with a maintenance station configured tomaintain the ejector head. Including a maintenance architecture thatdoes not interrupt the printing process and that does not significantlyincrease the footprint of the printing system would be beneficial.

SUMMARY

A three-dimensional object printing system with an incorporatedmaintenance system includes a track, a cart that moves along the track,and a recharging station positioned opposite the track. The cartincludes a platform, a cleaning device, a rechargeable power supply, anda controller. The cleaning device is configured to remove material froma surface of the printing system as the platform passes by the surface.The rechargeable power supply is configured to be selectively connectedto the cleaning device, and is also configured to be recharged viainductive charging. The controller is operatively connected to therechargeable power supply and the cleaning device, and is configured toselectively connect the rechargeable power supply to the cleaning deviceand operate the cleaning device to clean the surface. The rechargingstation is configured to inductively charge the rechargeable powersupply when the cart passes by the recharging station.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the present disclosure areexplained in the following description, taken in connection with theaccompanying drawings.

FIG. 1 is a perspective image of an exemplary embodiment of athree-dimensional printing system according to the disclosure.

FIG. 2 is a schematic diagram of another exemplary embodiment of athree-dimensional printing system according to the disclosure.

FIG. 3 is a schematic of an exemplary embodiment of a cart that movesthrough a three-dimensional printing system according to the disclosure.

FIG. 4 is a front view of another embodiment of a cart that movesthrough a three-dimensional printing system according to the disclosure.

FIG. 5 is a perspective view of an exemplary embodiment of carts thatmove through a three-dimensional printing system according to thedisclosure.

FIG. 6 is a perspective view of another embodiment of a cart that movesthrough a three-dimensional printing system according to the disclosure.

FIG. 7 is a schematic of another exemplary embodiment of a cart thatmoves through a three-dimensional printing system according to thedisclosure.

FIG. 8 is a perspective view of another embodiment of a cart that movesthrough a three-dimensional printing system according to the disclosure.

FIGS. 9 and 10 are side views of additional different exemplaryembodiment of a cart that moves through a three-dimensional printingsystem according to the disclosure.

FIG. 11 is a rear view of a known mobile cart that moves through aprinting system.

FIG. 12 is a perspective image of a known printing system.

DETAILED DESCRIPTION

For a general understanding of the present embodiments, reference ismade to the drawings. In the drawings, like reference numerals have beenused throughout to designate like elements.

FIG. 1 illustrates an exemplary embodiment of a three-dimensional objectprinter 100 that incorporates at least one mobile cart 102. The printer100 includes a first track 104, a second track 106, and at least oneprinting station 108 positioned opposite a first portion 110 of thetrack 104. The mobile cart 102 includes a platform 112 and wheels 114.The platform 112 is configured to support material for forming athree-dimensional object, while the wheels 114 connected to the platform112 are configured to engage and roll along the first track 104.

In general operation, the mobile cart 102 moves along the first track104 past the printing station 108, which includes at least one ejectorhead configured to eject material onto the platform 112 of the mobilecart 102 to form a three-dimensional object. The second track 106 isconfigured to support at least one maintenance cart (not shown),described in further detail below. During a maintenance operation,maintenance carts can be operated to move from the second track 106 tothe first track 104 and pass by the ejector heads of the station 108 toperform a maintenance operation on the ejector heads. In otherembodiments, the printer does not include a second track, andmaintenance carts move along the first track 104 in conjunction with themobile cart 102.

Ejector heads for three-dimensional printing object systems typicallyrequire maintenance over extended use, such as at regular intervals,after a predetermined number of printing operations, or upon detectionof a maintenance issue, in order to maintain accuracy, efficiency, andoperability necessary for three-dimensional object printing. Ejectorheads can become obstructed or clogged with extraneous material, foreignmaterials can contaminate or damage ejector heads, and material canbuild up on the track 104 or other portions of the printing system 100and interfere with the printing operation.

The tracks in a printing system may also require regular maintenancethat includes removing debris, such as material ejected by the ejectorheads, and inspecting tolerances or other conditions of the tracks.Printing stations may require servicing, recalibrating, or repair, andmobile carts can require servicing or assistance upon becoming stuck.Furthermore, in the event of a power failure, such as in a mechanicalfault or other fault condition, being able to proceed with maintenanceprocedures without interruption would be beneficial since aninterruption in proper maintenance of the printing system can result indamage to the printing system or printed objects. Additionally, benefitswould arise from the coordination of the performance of differentmaintenance tasks in order to reduce an impact that such processes haveon the printing process of the printing system.

FIG. 2 illustrates a schematic view of a three-dimensional objectprinting system 200 that incorporates a maintenance system thatcoordinates well with the printing process performed by the printingsystem 200. The system 200 includes at least one platform, such as theplatforms 202 a-e, a first track 204, an ejector head 206, a secondtrack 208, a switch 210, a recharging station 212, and a controller 214.In the embodiment of FIG. 2, platforms 202 a and 202 b are buildplatforms configured with a build platen to support an object beingproduced by the system, while platforms 202 c-202 e are maintenanceplatforms. Each of the platforms 202 a-e includes a plurality of wheels(not shown, see, e.g., FIG. 3) or other mobility mechanisms that areconfigured to enable the platforms to move along the first and secondtracks 204, 208 and through the system 200. The platforms 202 a and 202b include a magnet within a housing like the one described above withregard to FIG. 12 to enable the linear motors along the tracks 204, 208to propel the platforms along the tracks. Other types of propulsionsystems, such as motors powering the plurality of wheels of a platform,conveyers, or blowers are also contemplated. Other types of mechanismsthat enable the platforms to move along the first track 204, such assliding surfaces, air cushions, or other suitable mechanisms, inaddition to or instead of the plurality of wheels. The reader shouldunderstand that in the present embodiment, the first track 204 is acontinuous loop, and the process direction 216 refers to a direction ofmotion around the loop which, in FIG. 2, is counter-clockwise.

The ejector head 206 is configured to eject material for forming athree-dimensional object, and is positioned opposite a first portion 218of the first track 204. As illustrated in FIG. 2, the first portion 218includes multiple printing stations in addition to the ejector head 206,such as a planarizing station 220, a UV cure station 222, and an imageanalysis station 224, but other configurations and numbers of printingstations are also contemplated. In one embodiment, at least one printingstation is located opposite another portion of the first track 204spaced apart from the first portion 218. Although illustrated as asingle ejector head, the reader should understand that the ejector head206 can be an array of ejector heads. Moreover, the system 100 caninclude additional ejector heads or arrays of ejector heads positionedopposite the first track 204.

The controller 214 is operatively connected to the ejector head 206 andis configured to operate the ejector head as the build platforms inplatforms 202 a-202 e move along the first track 204 past the ejectorhead in the process direction 216. The controller 214 is alsooperatively connected to other printing stations and is configured toperform other printing operations via the other printing stations. Theconnections between the controller and the other printing stations220-224 are not shown in FIG. 2 for the purpose of clarity.

The system 200 includes at least one maintenance platform, such as theplatforms 202 c-e. Maintenance platforms are operable to perform anoperation on various portions of the printing system 200 including thefirst and second track 204, 208, printing stations, such as the ejectorhead 206 and UV curing station 222, and other platforms in the printingsystem 200. In this embodiment, a second portion 226 of the second track208 is configured to support maintenance platforms to enable amaintenance platform, such as the platform 202 d, to remain on thesecond portion 226 during a time period in which the platform 202 d isunused, and also includes a recharging station 212. The second track 208can also include other maintenance cart stations (not pictured), such asa waste receptacle, or other stations configured to facilitate use ofthe maintenance platforms 202 c-e. In another embodiment, the printer200 does not include a second track, so the maintenance stationsdescribed above are positioned opposite a portion of the first track204, and the first track 204 also supports the maintenance carts 202 c-ewhen not in use with a printing station.

In the embodiment of FIG. 2, the second track 208 is coupled to thefirst track 204 at a first position 228 to enable maintenance platformsto move from the second track 208 to the first track 204. The firstposition 228, on the first track 204, is before the first portion 218 inthe process direction 216 so a maintenance platform moving from thesecond track 208 to the first track 204 passes by the first portion 218when continuing to move along the first track 204. In this embodiment,the maintenance platforms 202 c-e are optionally self-propelled with apropulsion device, such as power source 502, motor 506, and drive wheel508 (FIG. 5), which enables the platform to move along the first track204 or the second track 208. In one embodiment, the maintenanceplatforms 202 c-e include magnets positioned within a housing of theplatform, similar to the build platforms 202 a and 202 b and the cartillustrated in FIG. 17, or other propulsion mechanisms. The maintenanceplatforms 202 c-e can activate the optionally self-propelled propulsiondevice if, for example, the entire system loses power, or if the cartneeds additional propulsion in a case when the propulsion mechanismtypical of carts 202 a-b is not sufficient.

The controller 214 is further configured to operate a maintenanceplatform to perform an operation when the maintenance platform is at adesired location within the printing system 200. In another embodiment,maintenance platforms each include an onboard controller configured tooperate the platform within the printing system in addition to orinstead of the controller 214. A particular platform can be operable toperform a particular type of operation or can be operable to perform avariety of operations. For instance, the printing system 200 can includeone or more maintenance platforms that are each operable to perform adifferent maintenance operation, one or more maintenance platforms thatare each operable to perform a plurality of operations, or both.

The first track 204 is selectively coupled to the second track 208 at asecond position 230 that is after the first portion 218 in the processdirection 216. In the present embodiment, the switch 210 is operable toselectively couple the first and second tracks 204, 208 at the secondposition 230, but other selective coupling mechanisms are alsocontemplated. The controller 214 is operatively connected to the switch210, and is further configured to operate the switch 210 to returnmaintenance platforms to the second track 208, and to enable mediaplatforms to remain on the first track 204. In another embodiment, theonboard controller of maintenance platforms 202 c-e is configured tooperate the switch 210 via, for example, a wireless communicationdevice, a selective electrical connection, or any other acceptable typeof communication.

As illustrated in FIG. 2, when the second track 208 is coupled with thefirst track 204, another continuous loop is formed by the second track208 and the first portion 218 of the first track 204. In the presentembodiment, the maintenance platforms 202 c-e move along the othercontinuous loop in a clockwise direction such that both the maintenanceplatforms 202 c-e and the build platforms 202 a and 202 b move along thefirst portion 218 in the same direction. While this embodiment includestwo continuous loops, other embodiments can include other numbers ofcontinuous loops. In one embodiment, different maintenance platforms,such as platforms operable to perform different operations, areconfigured to move along different continuous loops. In anotherembodiment, one or more printing stations or maintenance stations arepositioned on a portion of a continuous loop so other platforms are ableto move along a different loop while a particular platform engages withthe station. The maintenance carts 202 c-e, when moving around theprinting system 200, are not limited by a direction of travel, and maytravel in any direction or path around the tracks 204, 208 that enablesthem to perform maintenance functions. The controller 214 may directother carts to take a different path or direction to facilitate the useof a maintenance cart for a specific function.

Maintaining the printing stations and tracks while minimizinginterruptions in the printing process of the system 200 can beneficiallyenable a steady workflow of printing operations, and a decrease indowntime for printing station upkeep. Maintenance platforms should notcollide with or impede the movement of other platforms. Advantageously,the controller 214 can be further configured to coordinate movement ofmaintenance platforms 202 c-e with the movement of the build platforms202 a and 202 b. In other words, the controller 214 can be configured toschedule an operation on a printing station during a period of time whena build platform is not occupying a printing station. For example, thecontroller 214 can schedule operations at predetermined intervals, aftera predetermined number of printing operations, upon detection of amaintenance fault, such as a clog or contamination, or before or after aparticular printing operation.

In another embodiment, onboard controllers on the maintenance platformsenable the maintenance platforms to move and operate within the printingsystem 200 at least partially independent from the controller 214. Inone embodiment, the onboard controllers of the maintenance platforms arefurther configured to communicate with each other or the controller 214to coordinate movement through the printing system 200. In anotherembodiment, an onboard controller of a maintenance platform isconfigured to operate independently from other controllers.

Different information about a condition of the printing system 200 maybe more easily accessible to different components. For example, materialdebris on the first track 204 may be more readily discovered by amaintenance platform inspecting the first track 204 than by a diagnosticsensor on the ejector head 206. Furthermore, a component that discoversinformation may not be optimal for performing an operation. Forinstance, a maintenance platform can detect that material dripped ontothe first track 204 from the ejector head 206 and that the ejector head206 should be cleaned. However, the maintenance platform may already bepast the ejector head 206 when this condition is detected. Rather thantravelling all the way around the second continuous loop, the operationof cleaning the ejector head 206 or the first track 204 may be moreefficiently performed by another maintenance platform that is not yetpast the ejector head 206. Therefore, providing for communicationbetween maintenance platforms and other components of the printingsystem 200 is beneficial.

Because the second track 208 is integrated with the first track 204 soboth maintenance platforms 202 c-e and build platforms 202 a and 202 bpass through the first portion 218, a footprint of the printing system200 is smaller than systems having a maintenance station that isseparate from the printing stations. Further, the integrated nature ofthe maintenance platforms 202 c-e with the workflow of the printingprocess eliminates the need to connect and setup a maintenance station,such as a maintenance cabinet, that may need to be individually moved toand configured to operate with each individual printing station. Theprinting system 200 according to the present disclosure enablesdifferent operations to be performed on different printing stationswhile eliminating the often time consuming and complicated setupprocedures involved in conventional maintenance systems.

FIG. 3 illustrates a schematic view of an exemplary embodiment of a cart300 according to this disclosure. The cart 300 includes a platform 302,a plurality of wheels 304, a power supply 306, a propulsion device 308,a controller 310, a cleaning device 312, and a communication device 314.In different embodiments, one or more of the components 306-314 ishoused within the platform 302, or is mounted above or below theplatform 302. In one embodiment, the cleaning device 312 can beimplemented with devices that are actuated to remove debris, while inother embodiments, the cleaning device 312 can include a surfaceconfigured to receive material ejected from the ejector head 206 (FIG.2) in order to form a three-dimensional object. Other types of cleaningdevices are also contemplated.

The plurality of wheels 304 are operatively connected to the platform302 and enable the cart 300 to move along rails 316 in a printing systemas described above with regard to the precision rails 38 in FIG. 11. Inanother embodiment, the cart 300 includes slide surfaces configured toslide along slide rails similar to slide surfaces 18 and track rails 22as illustrated in FIG. 11 in addition to or instead of the plurality ofwheels 304. The propulsion device 308 is, for example, an actuator and awheel operatively connected to the actuator. The device 308 isconfigured to drive the wheel and move the cart 300 along the track 318.In other embodiments, the propulsion device 308 can include, forexample, a magnet of the type described above that operatively connectswith actuators within a housing of the track 318, or other propulsionmechanisms. The controller 310 is operatively connected to thepropulsion device 308, and is further configured to selectively connectthe propulsion device 308 with the power supply 306 to enable the cart300 to move in an optionally self-propelled fashion.

The power supply 306 is a rechargeable power source that is selectivelyelectrically connected to an actuator, and is configured to provideelectrical power to other components of the cart 300 including thepropulsion system 308, controller 310, cleaning device 312, andcommunication device 314. Any acceptable rechargeable power source canbe utilized. In an example, the power supply 306 is a lithium ionbattery, lithium air battery, lithium metal battery, lithium sulfurbattery, or metal-air battery. In this embodiment, the power supply 306is configured to be charged by inductive charging via, for example awireless charging device, and includes, for example, an induction coil(not shown) configured to receive wireless power from a rechargingstation of the printing system. In another embodiment, the power supply306 includes a charging connection interface (not shown) that isconfigured to couple with a charger connection interface of a rechargingstation of the printing system.

The communication device 314 enables the controller 310 to communicatewith controllers of other carts in the printing system, or a centralcontroller of the printing system. In one embodiment, the cart 300 doesnot include a communication device, and is thus independent of othercarts and the central controller. The communication device can includeany acceptable type of communications mechanisms such as an antenna andtransmitter, infra-red receiver and emitter, wireless radio, or thelike.

The cleaning device 312 is operable to perform at least one operation onthe printing system or on another cart in the printing system. Thecleaning device 312 can include one or more separate mechanisms forperforming different operations, and the cart 300 can include additionalcleaning devices 312 as desired. Various types of cleaning devices 312are contemplated, included the cleaning device described in theembodiments set forth below.

FIG. 4 illustrates an exemplary embodiment of a cart 400 positioned at arecharging station 402 according to this disclosure. In this embodiment,the cart 400 includes a first component 404 that has a rechargeablepower supply and a propulsion component, and a second component 406 thathas a cleaning device. The power supply is positioned within the firstcomponent 404 to enable an electrical connection between the powersupply and the recharging station 402. The recharging station 402 isconfigured to electrically connect to a power supply of a cart by anyacceptable mechanism to enable the power supply of the cart to recharge,such as by a lead connection or by a wireless induction connection. Acontroller and communication device can be housed in either component404, 406, and in other embodiments, different elements are housed withindifferent components. While illustrated as being positioned below thetrack 318 in FIG. 4, in other embodiments, the recharging station 402 ispositioned in other locations such as, for example, laterally offsetfrom the track 318, or above the track 318. In one embodiment, at leasta portion of the recharging station, such as a charging connectioninterface or a wireless induction coil, is at least partially positionedwithin or integral with the track 318.

In one embodiment, the recharging station 402 is configured tocommunicate with a controller onboard a cart, or a central controller ofthe printing system, and is further configured to recharge the powersupply of a cart with reference to information received via suchcommunication. In one example, the controller onboard a cart providesthe recharging station with information indicative of a condition of thepower supply that facilitates recharging the power supply in anefficient manner. In another example, the controller of the printingsystem can prioritize recharging the power supply to a desired powercondition relative to a maintenance task within the printing system. Forexample, the recharging station 402 can selectively recharge the powersupply to less than a completely recharged condition to prioritizeperformance of a maintenance operation in the system.

In one embodiment, illustrated in FIG. 5, a cart 500 has a couplingmember 504 mounted at end of the cart and a propulsion system 506 thatincludes a power source 502, a motor 506, and a drive wheel 508. Thecoupling member 504 is configured to engage with or bear against anothercart 510. In different embodiments, the coupling member 504 can be ahitching member, a pushing surface, a magnetic coupler, or any otheracceptable coupling mechanism. The drive wheel 508 is configured to rollalong a track housing 512 to propel the cart 500 along the tracks 514 ofthe printing system when operatively connected to an onboard powersupply 502. Advantageously, the drive wheel 508 is configured to produceenough torque to move both the cart 500 and the other cart 510 along thetracks 514. The coupling member 504 is configured to connect with theother cart 510 to direct the output of the propulsion system 506 againstthe cart 510 and move both carts along the tracks 514 of the printingsystem. This configuration enables the cart 500 to act as a tug to moveand reposition other carts within the printing system.

In one example, in response to a power failure of the actuators in thetrack housing 512 (not illustrated) that strands cart 510 on the tracks514, the cart 500 can be dispatched to couple with the cart 510 andreposition the cart 510 to a different location in the printing system.In another example, in response to a mechanical failure of a wheel orpropulsion system of the cart 510 that interferes with the cart'smovement through the printing system, the cart 500 can be dispatched toengage and move the cart 510 to a maintenance area. In a furtherexample, a wheel or propulsion device of the further cart 510 has becomedislocated with respect to the tracks 514, and the cart 500 can bedispatched in order to relocate the further cart 510 with respect to thetracks 514.

Returning to FIG. 3, the sensor 320, which is mounted to the platform302, is configured to generate an electrical signal that corresponds toa condition of a portion of the printing system, such as a surface to becleaned. The sensor 320 can include, for example, one or more camerasconfigured to generate image data corresponding to portions of theprinting system, such as the rails 316 or track 318, another cart, or aprinting station. In an embodiment, the controller 310 is operativelyconnected to the sensor 320 to receive image data generated by thesensor 320 and is further configured to analyze the image data to, forexample, detect debris, locate another cart, or assess a condition of aprinting station or another portion of the printing system. The sensor320 can include an accelerometer configured to, for example, detectdebris on a rail 316 or track 318 by generating an electrical signal inresponse to motion resulting from a discontinuous surface due to thedebris. The sensor 320 can also include other types of sensors, such asa sensor configured to detect a maintenance condition of an ejector inan ejector head.

In one embodiment, the controller 310 is configured to transmit theelectrical signal corresponding to the condition of the portion of theprinting system to, for example, a central controller of the printingsystem, via the communication device 314, to enable the cart 300 to actas a remote diagnostic apparatus. Such a central controller can beconfigured to diagnose a maintenance condition of the printing systemand take appropriate action. In other embodiments, inspection anddiagnosis of the printing system is shared between one or more carts andthe central controller. In an example, a first cart detects debris on aportion of a track via an accelerometer and transmits this informationto the central controller via a communication device. In response, thecentral controller operates another cart to generate image data of theportion of track with a camera in order to diagnose further the statusof the track.

The cleaning device 312 is operable to perform a maintenance operationon the printing system. In one embodiment, the controller 310 isconfigured to connect the cleaning device 312 selectively to the powersupply 306 and operate the cleaning device 312 to perform themaintenance operation in response to the electrical signal generated bythe sensor 320. In another embodiment, the controller 310 is configuredto operate the cleaning device 312 to perform the maintenance operationin response to an electrical signal corresponding to operationinstructions received via the communication device 314. In anotherembodiment, the controller 310 is configured to operate the cleaningdevice 312 in concert with other carts within the printing system. Inanother embodiment, the controller 310 operates the cart 300 to performmaintenance operations independently. Various types of maintenanceoperations are contemplated, including the specific examples describedbelow.

In one example of a maintenance operation, debris, such as materialejected from an ejector head, or other matter, is removed from a rail316 or track 318. In such case, the maintenance device can include, forexample, a plow or scraper configured to remove debris, as illustratedin FIG. 6, or a powered debris removal device, such as a powered brushas illustrated in FIG. 7. FIG. 7 illustrates a cart 700 that includes anactuator 702, a set of brushes 704, 706, a vacuum source 708, areceptacle 710, a vacuum manifold 712, and a set of nozzles 714. 716.Other components, such as an onboard power supply, controller, sensor,propulsion device, communication device, and cleaning device can also beincluded with the cart 700, but are omitted in FIG. 7 for the sake ofclarity.

The brushes 704, 706 of cart 700 are operatively connected to theactuator 702, which is configured to move the brushes 704, 706 and cleanthe rails 316 and track 318. The actuator 702 can be selectivelyconnected to a power supply or a controller configured to operate theactuator to move the brushes 704, 706. The brushes 704, 706 areconfigured and arranged to enable the brushes 704, 706 to contact debrison the rails 316 and track 318 and remove or dislodge the debris as thecart 700 moves in the process direction 720. The reader shouldunderstand that abrasive surfaces, other than brushes, can be configuredfor selective engagement with the rails and tracks to clean them. Thevacuum source 708 is configured to generate a vacuum, and the vacuummanifold 712 is configured to distribute the vacuum among the nozzles714, 716. The nozzles 714, 716 are configured and arranged to enable thevacuum to draw the debris or material removed or dislodged from therails 316 and track 318 through the manifold 712 and into the receptacle710. The receptacle 710 is configured to store the vacuumed debris, andcan further include, for example, a closable lid or removable bin (notillustrated) or other mechanism that facilitates removal of the storeddebris.

While FIG. 7 illustrates the brushes 704, 706 as being in front of thecart 700 in the process direction 720, and the nozzles 714, 716 as beingbehind the cart 700 in the process direction, in other embodiments,nozzles and brushes can be positioned at various acceptable locations aswould be understood by one of ordinary skill in the art. In an example,brushes can be positioned between nozzles and a rear of the cart 700, ornozzles can be positioned between the front of the cart and brushes.Generally, positioning brushes in front of nozzles in the processdirection enables the nozzles to capture debris loosened by the brushes,but other configurations, such as one in which the nozzles are in frontof brushes, and one in which the brushes include nozzles are alsocontemplated. Other types of maintenance devices that enable clearingdebris are also contemplated, such as a device configured to dispense acleaning agent or solvent that facilitates the removal of debris, adevice configured to dispense an agent, heat, or light, in order tosolidify or liquefy debris in order to facilitate its removal, or otheracceptable debris removal mechanisms.

In an example of an operation on a printing station, when maintenanceplatform 202 c is positioned opposite the ejector head 216 (FIG. 2), thecontroller 214 is configured to operate the ejector head 206 to ejectmaterial onto the maintenance platform 202 c. Such ejection can purgematerial and contaminants from the ejector head 206, remove or prevent aclog, clean material from the ejector head 206, or prevent material fromaccumulating on, for example, the first track 204.

FIG. 8 illustrates an exemplary embodiment of a maintenance platform 800that includes a plurality of wheels 802 configured to engage with atrack 804 and a tray 806 configured to receive material ejected from anejector head. The tray 806 has a height 808 configured to retain ejectedmaterial in the tray. In one embodiment, the platform 800 is configuredto stop beneath the ejector head to enable the ejector head to purgematerial into the tray 806. While integrating maintenance platforms withmedia platforms to perform operations as described above is beneficialto reducing delay in the printing process, purging material from anejector head may result in a delay before the ejector head is againusable for printing onto a media platform. In another embodiment, theplatform 800 remains in motion along the track 804 while the ejectorhead purges material into the tray 806 as the platform 800 passes theejector head, thereby further reducing or even eliminating the delay.The platform 800 can move along the track 804 at full process speed, orat a reduced rate of speed to facilitate the purging of material fromthe ejector head.

In another example of a maintenance operation, a face of a printingstation, such as the ejector head 206 (FIG. 2), is wiped to removeextraneous material or contaminants, remove or prevent clogs, andotherwise maintain the printing station. The controller is configured tomove maintenance platform 202 c past the ejector head 206 and operatethe maintenance platform 202 c to wipe a face of the ejector head 206,for example, via a wiping mechanism. FIG. 9 illustrates an exemplaryembodiment of a maintenance platform 900 that is operable to wipe anejector head 902. The platform 900 includes wheels 904 configured toengage with a track 906 and a wiper 908 connected to the platform 900.The wiper 908 is positioned and configured to wipe the ejector head 902when the platform 900 is moved along the track 906 past the ejector head902. The wiper 908, in this embodiment, is a rigid wiper that wipes asthe platform 900 moves along the track. Other types of wipers are alsocontemplated, such as wipers actuated by passive or active actuators.

Performing different operations in sequence or in conjunction can bebeneficial. In the illustrated embodiment, the platform 900 furtherincludes a tray 806 configured to receive material purged or wiped fromthe ejector head 902, and the wiper 908 is connected to the tray 806.Thus, a material purging operation to purge material from the ejectorhead 902 before performing a wiping operation enables the tray 806 tocollect the cleared material as the tray passes the ejector head 902before the wiper 908. The subsequent wiping of the ejector head 902 withthe wiper 908 helps ensure the face of the ejector head 902 is clean.Both purging and wiping the ejector 902 in this order enables theejector 902 to be both ready to operate efficiently and to be free frompurged material.

In a further example of a maintenance operation, covering an ejectorhead during a period of time in which the ejector head is unused can bebeneficial to protect the ejector head from damage and contamination andto inhibit material within the ejector head from solidifying andpotentially forming clogs. In another example, some types of materialsejected by an ejector head, such as UV curing material, can be volatile,and covering the ejector head during periods of nonuse limits theexposure of such materials to the environment.

FIG. 10 illustrates an exemplary embodiment of a platform 1000 thatincludes wheels 1002, covering members 1006 a and 1006 b, and anactuator 1008. The wheels 1002 are configured to engage with and rollalong the track 1004. The covering members 1006 a and 1006 b areconfigured to cover ejector heads 1010 a and 1010 b. While the platform1000 is illustrated as including two covering members 1006 a and 1006 b,the reader should understand that the platform 1000 can includedifferent numbers of covering members to comport with different numbersof ejector heads in an ejector head array. The actuator 1008 isoperatively connected to the covering members 1006 a and 1006 b and isconfigured to cover the ejector heads 1010 a and 1010 b with thecovering members 1006 a and 1006 b when the platform 1000 is positionedopposite the ejector heads 1010 a and 1010 b. While FIG. 10 illustratesthe two covering members 1010 a and 1010 b as being operativelyconnected to a single actuator 1008, other numbers of covering memberscan be connected to a single actuator. In one embodiment, each coveringmember is operatively connected to a respective actuator to enableseparate ejector heads to be covered or uncovered independently of oneanother. The actuator 1008 is, for example, operatively connected to thecontroller 212 (FIG. 2) or the onboard controller 310 (FIG. 3), whichcan be configured to operate the actuator 1008 to cover the ejectorheads 1006 a and 1006 b during a period of time in which the ejectorheads 1010 a and 1010 b are unused, and can further be configured touncover the ejector heads 1006 a and 1006 b to enable the platform 1000to depart from the ejector heads 1006 a and 1006 b. Other types ofcovering mechanisms are also contemplated such as, for example, acovering mechanism configured to respond to a passive actuator, acovering mechanism configured to selectively cover a particular ejectorhead, and other types of covering mechanisms.

Inspecting the printing system in conjunction with performingmaintenance operations or printing operations may be beneficial. In oneexample, a maintenance operation is performed in response to aninspection that diagnosed a maintenance condition of the printingsystem. In another example, an inspection is performed to determinewhether a maintenance operation was successful. In a further example, aprinting operation is not scheduled until an inspection indicates aprinting station is in a satisfactory maintenance condition. In oneembodiment, the controller 212 (FIG. 2) or onboard controller 310 (FIG.3) coordinates inspections, maintenance operations, and printingoperations within the printing system to facilitate efficient printing.

Those skilled in the art will recognize that numerous modifications canbe made to the specific implementations described above. Therefore, thefollowing claims are not to be limited to the specific embodimentsillustrated and described above. The claims, as originally presented andas they may be amended, encompass variations, alternatives,modifications, improvements, equivalents, and substantial equivalents ofthe embodiments and teachings disclosed herein, including those that arepresently unforeseen or unappreciated, and that, for example, may arisefrom applicants/patentees and others.

What is claimed is:
 1. A cart that moves through a three-dimensionalobject printing system comprising: a platform having wheels to enablethe platform to move along a track; a cleaning device configured toremove material from a surface as the platform passes the surface; arechargeable power supply configured to be connected to the cleaningdevice; a motor operatively connected to at least one of the wheels ofthe cart; and a controller operatively connected to the rechargeablepower supply and the cleaning device, the controller being configured toconnect the rechargeable power supply to the cleaning device selectivelyto operate the cleaning device to clean the surface and to connect therechargeable power supply to operate the motor to move the platformalong the track, the operation of the cleaning device and the operationof the motor being independent of one another.
 2. The cart of claim 1further comprising: a communications device configured to transmit andreceive electrical signals; and the controller is operatively connectedto the communications device, the controller being further configured tooperate the cleaning device with reference to data received through thecommunications device.
 3. The cart of claim 2 further comprising: asensor mounted to the platform, the sensor being configured to generatean electrical signal corresponding to the surface; and the controllerbeing operatively connected to the sensor, the controller being furtherconfigured to connect the cleaning device to the rechargeable powersupply and operate the cleaning device to remove the material from thesurface in response to the electrical signal generated by the sensorindicating material on the surface.
 4. The cart of claim 3, the sensorfurther comprising: a camera; and the controller being operativelyconnected to the camera to receive image data generated by the camera,the controller being further configured to analyze the image datareceived from the camera to detect material on the surface to becleaned.
 5. The cart of claim 3, the sensor further comprising: anaccelerometer; and the controller being operatively connected to theaccelerometer to receive data generated by the accelerometer, thecontroller being further configured to analyze the data received fromthe accelerometer to detect material on the surface to be cleaned. 6.The cart of claim 3, the controller being further configured to operatethe communications device to send data corresponding to the electricalsignal generated by the sensor to the external device.
 7. The cart ofclaim 1, the rechargeable power supply being further configured to berecharged by an inductive charger.
 8. The cart of claim 7 furthercomprising: a member configured to contact another cart to enable thewheel to move the other cart along the track as the wheel moves theplatform along the track.
 9. The cart of claim 1, the cleaning devicefurther comprising: an abrasive cleaning surface; an actuatoroperatively connected to the abrasive cleaning surface; and thecontroller being further configured to connect the actuator to therechargeable power supply selectively to operate the actuator and movethe abrasive cleaning surface into contact with a track along which theplatform moves.
 10. The cart of claim 9, the cleaning device furthercomprising: a vacuum source; a receptacle operatively connected to thevacuum source to store debris pulled by the vacuum source; and thecontroller being further configured to selectively connect the vacuumsource to the rechargeable power supply to operate the vacuum source andmove material removed from the surface by the abrasive cleaning surfaceinto the receptacle.
 11. The cart of claim 1, the cleaning devicefurther comprising: a wiper; an actuator operatively connected to thewiper; and the controller being further configured to selectivelyconnect the actuator to the rechargeable power supply to operate theactuator and move the wiper into contact with a surface of an ejectorhead surface as the platform passes the ejector head.
 12. Athree-dimensional object printing system comprising: a track; a cartthat includes: a platform; a cleaning device configured to removematerial from a surface as the platform passes the surface; arechargeable power supply configured to be connected to the cleaningdevice and configured to be recharged by inductive charging; and acommunications device configured to transmit and receive electricalsignals; a controller operatively connected to the rechargeable powersupply, the cleaning device, and the communications device, thecontroller being configured to connect the rechargeable power supply tothe cleaning device and to operate the cleaning device to clean thesurface with reference to data received from an external source throughthe communications device; and a recharging station positioned oppositethe track that is configured to inductively charge the rechargeablepower supply when the cart passes by the recharging station.
 13. Thethree-dimensional object printing system of claim 12, the cart furthercomprising: a sensor mounted to the platform, the sensor beingconfigured to generate an electrical signal corresponding to thesurface; and the controller being operatively connected to the sensor,the controller being further configured to connect the cleaning deviceto the rechargeable power supply and operate the cleaning device toremove the material from the surface in response to the electricalsignal generated by the sensor indicating material on the surface. 14.The three-dimensional object printing system of claim 13, the sensorfurther comprising at least one of: (i) a camera, the controller beingoperatively connected to the camera to receive image data generated bythe camera, the controller being further configured to analyze the imagedata received from the camera to detect material on the surface to becleaned; and (ii) an accelerometer, the controller being operativelyconnected to the accelerometer to receive data generated by theaccelerometer, the controller being further configured to analyze thedata received from the accelerometer to detect material on the surfaceto be cleaned.
 15. The three-dimensional object printing system of claim12, the cart further comprising: a wheel operatively connected to theplatform to move the platform along a track; an actuator operativelyconnected to the wheel; and the controller being further configured toselectively connect the actuator to the rechargeable power supply tooperate the actuator and move the platform along the track.
 16. Thethree-dimensional object printing system of claim 15 further comprising:a printing station operable to perform a printing operation; and anothercontroller that is operatively connected to the printing station, theother controller being configured to operate the printing station andselectively transmit an electrical signal to the communications deviceto schedule maintenance on the printing station.
 17. Thethree-dimensional object printing system of claim 15, the cart furthercomprising: a member configured to contact another cart to enable thewheel to move the other cart along the track as the wheel moves theplatform along the track.
 18. The three-dimensional object printingsystem of claim 12, the cleaning device further comprising: (i) anabrasive cleaning surface and a first actuator operatively connected tothe abrasive cleaning surface, (ii) a vacuum source and a receptacleoperatively connected to the vacuum source to store debris pulled by thevacuum source; and (iii) a wiper and a second actuator operativelyconnected to the wiper; and the controller is operatively connected tothe first actuator and the second actuator, the controller being furtherconfigured to connect selectively the first actuator to the rechargeablepower supply and operate the first actuator to move the abrasivecleaning surface into contact with a track along which the platformmoves, selectively connect the vacuum source to the rechargeable powersupply to operate the vacuum source and move material removed from thesurface by the vacuum source into the receptacle, and selectivelyconnect the second actuator to the rechargeable power supply and operatethe second actuator to move the wiper into contact with a surface of anejector head surface as the platform passes the ejector head.